Spyder3 S3-14 and S3-24 Monochrome Camera User's Manual
49
Teledyne DALSA
03-032-20117-01
2.
The d igital offset (
sdo
com m and ) enables the su btraction of the ―artificial‖ A/ D offset (the analog
offset) so that application of the PRNU coefficient d oesn’t result in artifacts at low lig ht levels d ue to
the offset valu e. You m ay w ant to set the
sdo
valu e if you are not u sing FPN correction bu t w ant to
p erform PRN U correction.
3.
Photo-Resp onse N on -Uniform ity (PRN U) coefficients (calcu lated u sing the
ccp
or
cpa
com m and s)
are u sed to correct the d ifference in resp onsivity of ind ivid u al p ixels (i.e. given the sam e am ou nt of
light d ifferent p ixels w ill charge u p at d ifferent rates) and the ch ange in light intensity across the
im age either becau se of the light sou rce or d u e to op tical aberrations (e.g. there m ay be m ore light in
the center of the im age). PRN U coefficients are m u ltip liers and are d efined to be of a valu e greater
than or equ al to 1. This ensu res that all p ixels w ill satu rate together.
4.
Backgrou nd su btract (
ssb
com m and ) and system (d igital) gain (
ssg
com m and ) are u sed to increase
im age contrast after FPN and PRN U calibration. It is u sefu l for system s that p rocess 8-bit d ata bu t
want to take ad vantage of the camera’s 12 bit d igital processing chain. For examp le, if you find that
you r im age is consistently betw een 128 and 255 DN (8 bit), you can su btract off 128 (
ssb 2048
) and
then m u ltip ly by 2 (
ssg 0 8192
) to get an ou tp u t range from 0 to 255.
Analog Signal Processing: Setting Analog Gain and Offset
All analog signal p rocessing chain com m and s shou ld be p erform ed p rior to FPN and PRN U calibration
and p rior to d igital signal p rocessing com m and s.
N ote: This com m and w ill invalid ate the LUT calibration for the 4k m od el of cam era. Use the
ssg
com m and instead .
Setting Analog Gain
Sets the cam era’s analog gain valu e. Analog gain is m u ltip lied by the analog signal to increase the signal
strength before the A/ D conversion. It is u sed to take ad vantage of the fu ll d ynam ic range of the A/ D
converter.
Camera Link Command
Parameter
Description
Notes
sag t f
t Tap selection. Use
0
for all tap s or
1
to
2
for ind ivid u al tap selection
f Gain valu e in a range from
–
10
to
+10
d B.
To retu rn the cu rrent analog gain setting, u se the
com m and
gcp
or
get
sag
.
Example
sag 0 5.2
Calibrating Camera Gain
Instead of m anu ally setting the analog gain to a sp ecific valu e, the cam era can d eterm ine ap p rop riate gain
valu es. This com m and calcu lates and sets the analog gain accord ing to the algorithm d eterm ined by the
first p aram eter.
